Newborn society of fetal urology grade 3 hydronephrosis is equivalent to preserved percentage differential function.
OBJECTIVE
In newborn hydronephrosis (HN), the level of differential function (%df) measured by diuretic renography (DR) is used to judge the need for pyeloplasty. As DR testing is complex, we sought to determine if grading the level of HN (Society of Fetal Urology grade, SFU Gr) by a simple ultrasound correlates with percentage differential function (%df) and thereby obviates the need to perform DR.


METHODS
Between 1990 and 2003 our institution prospectively enrolled all cases of fetal HN who showed unilateral newborn SFU Gr HN > or =3. The cases underwent standardized testing. DR was done using the method of Well-Tempered Renography which was then followed by ultrasound (US). The US studies were performed while the hydration induced by DR was in effect. The level of %df was categorized as preserved (> or =40%) or reduced (<40%). Cases were excluded if there was an additional urological abnormality (e.g. ureterocele).


RESULTS
There were 71 cases that met our study criteria. The SFU Gr HN was 3 (n=33) or 4 (n=38). Kidneys with SFU Gr 3 HN showed preserved %df (33/33,100%) (mean=50.1+/-3.6) significantly more often than kidneys with SFU Gr 4 HN (27/38, 71%) (mean=42.2+/-13.9) (RR=1.41, 95% CI (1.15-1.72), p<0.001).


CONCLUSIONS
In newborns with a history of fetal HN, the postnatal finding of SFU Gr 3 HN uniformly correlates with preserved %df. Standardized hydration prior to US study is done to assure consistency in measurement of the SFU Gr HN. Determining the duration of the relationship between SFU Gr 3 HN and preserved %df will require prospective, longitudinal studies.
Erickson
Bradley A
BA
Division of Urology, Children's Memorial Hospital, 2300 Children's Plaza, Chicago, IL 60614, USA. b-erickson@md.northwestern.edu
Maizels
Max
M
Shore
Richard M
RM
Pazona
Joseph F
JF
Hagerty
Jennifer A
JA
Yerkes
Elizabeth B
EB
Chaviano
Antonio H
AH
Kaplan
William E
WE
Cheng
Earl Y
EY